Fuel in oil

snowblind

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Hey, I just put a scrambler type trail bike together out of a 79 xs and all is good except for fuel draining into the crank case when the bike sits after a ride. The carbs and petcocks are freshly rebuilt. It seems to only leak when the bike is on its side stand. If I put a block of wood under the stand, to prop it up straighter, no problems. Has anybody else had, or heard of a problem like this?
Thanks
 

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Either the float valves are sticking or need to be replaced with better quality parts.

also your petcock might be leaking if you turn it off and it still fills the crankcase with gas.

This is a very common problem, try tapping on the side of the carburetors with a soft hammer or screwdriver. If that doesn't work you should open them backup and inspect the needle and seat, possibly replace.

Or I guess it could be that your float level is just set too high.
 
Seems to me, it’s only the contents of the bowls going in. It’s not filling up the crank case, but just draining the bowls. Float valves are oe, in excellent condition. Petcocks work as they should. No fuel flow when left in the on position. (Vac type petcocks). Never had a problem until I removed the center stand. It has 14” shocks on it and she’s got quite a lean on the side stand. I was wondering if the high carb is draining into the low and over flowing it? Ever seen this? Or anybody ever remove the crossover line?
 
Yes, I guess it is possible that the higher right carb is transferring it's fuel over to the lower left carb. I think I'd try fixing (modding) the sidestand so the bike doesn't lean over so much. I don't think there's much else you can do. The carbs weren't designed to hold fuel leaned way over like that.

I run longer than stock rear shocks on both my 650s. Although not as long as yours, I had to mod both sidestands so the bikes didn't lean over so far. I simply welded some steel plate to the bottom of the stand foot. Here's the early style stand I swapped onto my '83 next to the awful, ugly original. I welded about a 1/2" thick piece of plate to it's foot .....

04ypiqc.jpg
 
Hey, I just put a scrambler type trail bike together out of a 79 xs and all is good except for fuel draining into the crank case when the bike sits after a ride. The carbs and petcocks are freshly rebuilt. It seems to only leak when the bike is on its side stand. If I put a block of wood under the stand, to prop it up straighter, no problems. Has anybody else had, or heard of a problem like this?
Thanks

Hi snowblind and welcome,
Nice bike, it's diet must have lost it 80 lbs or so?
one way to fix the fuel leakage problem is to modify the gas tap.
Shorten the tap lever and file off the tap retaining plate nubbin so the lever can point straight UP to give a true OFF rather than relying on the vacuum auto-off.
About the rest of the bike:-
Shorty pipes will make the bike a right swine to tune.
Those pleated tapered pod air filters ain't compatible with the stock carbs for all they say XS on them, replace them with Unipods.
The stock front fender is also a fork brace, Yours ain't. Install an aftermarket tubular steel fork brace, especially for off-road use.
The front brake will work better if it's drilled full of holes.
 
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Shorten the tap lever and file off the tap retaining plate nubbin so the lever can point straight UP to give a true OFF rather than relying on the vacuum auto-off.
That all there is to it Fred? Have you done that? Is it really that easy?
 
Thanks guys, I will be making an extended side stand, just haven’t got to it.
That’s a good idea about the petcocks, I didn’t think of that. I think I’ll be doing that for sure. I don’t like to rely on the diaphragms. I have been debating a fork brace. Seems pretty sturdy so far, I don’t ride the bike very hard, mostly light trails and side roads around the farm. But that can change pretty quickly.
 
On the vacuum petcock what Fredintoon described is correct. On my 81 SH I tried the modification but did not like the short upside-down lever so made a completely new lever with the fuel paths cut in as a mirror image of the original. It then gives Prime Position as Off, Reserve as Reserve etc. It is hidden somewhere on this site.
 
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On the vacuum petcock what Fredintoon described is correct. On my 81 SH I tried the modification but did not like the short upside-down lever so made a completely new lever with the fuel paths cut in as a mirror image of the original. It then gives Prime Position as Off, Reserve as Reserve etc. It is hidden somewhere on this site.

Hi Paul,
my XS11 had mirrored gas taps. Swapping their innards over worked as you described.
 
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